Luis ate 4 slices of pizza. Nadia ate 5 slices. If Luis ate $\dfrac{4}{10}$ of the pizza, what fraction of the pizza was eaten?
Solution: If 4 slices represent $\dfrac{4}{10}$ of the pizza, there must have been a total of 10 slices. $\text{fraction of pizza eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ They ate ${9}$ out of $10$ slices. They ate $\dfrac{9}{10}$ of the pizza.